package cn.xyh.util;

import javax.imageio.ImageIO;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

/**
 * Created by Administrator on 2017/8/19 0019.
 */
public class CodeUtil extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        //这个方法实现验证码的生成
        BufferedImage bi = new BufferedImage(68, 32, BufferedImage.TYPE_INT_RGB);//创建图像缓冲区
        Graphics g = bi.getGraphics(); //通过缓冲区创建一个画布
        Color c = new Color(200, 150, 255); //创建颜色
         /*根据背景画了一个矩形框
          */
        g.setColor(c);//为画布创建背景颜色
        g.fillRect(0, 0, 68, 32); //fillRect:填充指定的矩形

        char[] ch = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".toCharArray();//转化为字符型的数组
        Random r = new Random();
        int len = ch.length;
        int index; //index用于存放随机数字
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < 4; i++) {
            index = r.nextInt(len);//产生随机数字
            g.setColor(new Color(r.nextInt(88), r.nextInt(188), r.nextInt(255)));  //设置颜色
            g.drawString(ch[index] + "", (i * 15) + 3, 18);//画数字以及数字的位置
            sb.append(ch[index]);
        }
        req.getSession().setAttribute("piccode", sb.toString()); //将数字保留在session中，便于后续的使用
        ImageIO.write(bi, "JPG", resp.getOutputStream());

    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        super.doGet(req, resp);
    }

    @Override
    public void init(ServletConfig config) throws ServletException {
        super.init(config);
    }
}
